Apparatus for heating fluids



A g. 25, 1936- 1.. A. MEKLER 2,051,880

I APPARATUS FOR HEATING FLUIDS Original Filed Nov.,22, l930 FIG; I

F'IGZ.

INVENTOR LEV A. MEKLER mozg gw T Patented Aug. 25, I936 v UNITED STATES PATENT OFFICE APPARATUS son nEA'l'ING-npms Lev A-.,Mekler, Chicago, Ill., asllgnor, by meslle assignments, to Universal Oil Products Company, Chicago, 11]., a corporation of Delaware Application November 22,1930, Serial No. 491.556

Renewed November 6, 1935 5 Claims. (01. 122-356) This invention relates to improvements in furnaces for heating fluids, and refers particularly,

to a means for controlling the rate of heat input into various portions of the heating element and means for increasing the effective heating surface in the radiant heat bank.

Other and further objects and advantages of 20 my invention will be apparent from the accompanying drawing and following detail description.

In the drawing, Fig. 1 is a cross-sectional view of a furnace provided with apparatus suitable 25 for carrying out my invention.

Fig. 2 is a sectional plan view taken on a line 2--2 of Fig. 1.

Referring in detail to the drawing, reference being made particularly to Fig. 1, I indicates 3 a furnace having a roof 2, rear wall 3 and front or firing wall 4, said roof and walls forming an enclosure for combustion chamber 5. A bailie wall 6 may be disposed within combustion chamber adjacent rear wall 3 providing a space I 5 between said rear wall and the baflie 6. A flue 8 may connect the lower portion of the space I to a suitable stack (not shown). If desired, a

plurality of fluid passageways or tubes 9 may be" positioned within the space 1 and may be adapt- 40 ed to be heated by convection or sensible heat from combustion chamber 5.

A combustion block It may be positioned in the lower front portion of the furnace I and may be provided with central combustion tunnel II and auxiliary tunnels l2 and i3, which latter tunnels may be provided with suitable dampers l4 and I5, respectively. Fuel may be introduced into central tunnel H by means of 50 burner l6, said fuel being conducted to said burner from a suitable source of fuel supply.

(not shown) by means of pipe II. It is to be understood that gas, oil, pulverized coal, or any other fuel may be burned, but preferably the 55 fuel must be burned under such conditions that a high degree of radiant heat is given ofi into combustion chamber 5. g

A bailie i8 may be disposed within combustion chamber 5 and a plurality of fluid passageways .or tubes i9 may be positloned'in the space 20 I between the baiile l8 and the front wall 4.

a plurality of tubes 2| may be positioned iii one or more rows adjacentthe 'roof 2 of the furnace and, as a feature of my invention, I may dispose a substantially semi-cylindrical or trough-like protector 22 adjacent the lower surfacesof each of said tubes and spaced from said tubes by suitable arms or spacers 23. Spaces 24 i may be provided between adjacent tubes 2l' through which gases of combustion from combustion chamber 5- may-pass, and in order to control the quantity of said gases which pass adjacent the tubes 2| with respect to the position of each of the tubes in the row or rows I .may provide a plurality of ba'flle plates 25 be- 20 tween said adjacent tubes. It can readily be seen that the draft which may tend to draw the combustion gas from the combustion chamber 5 to the space I, the flue 8 and the stack will be greater in the vicinity of those tubes located 25,

adjacent baflle wall 6 and will progressively di minish' in intensity along the row of tubes toward the front end of the-combustion chamber. To compensate for this inequality in draft along the row of tubes 2] I may provide a relatively greater number of baflleplates 25 adjacent those tubes near the wall 6 than those tubes adiacent wall 4. In this manner substantially the same quantityof hot combustion gases will come into contact with all the tubes which constitute the row.

In'heating fluids the same are usually confined x within a cylindrical or substantially zone suchas a tube or shell, and when said,

"cylindrical zone-is exposed to radiant heat the 40 area of the surface of said tube or shell exposed to the radiant heat will be substantially equal to the projected area of said tube or shell upon a plane parallel to the plane of the source of heat. In other words, the effective area of the tube will be equal to the product of its length by its diameter, which as can readily be seen com prises only about one-third .of the total area of the tube. In other words, where a tube is exposed to radiant heat the greatest portion of heat transferred to the tube takes place over about one-third the surface of the tube. Whereas, a relatively smaller portion of the heat transfer takes place over the remaining two-thirds of the tube.

To uniformly distribute the heat about the entire area of the surface of the tube is an object of my invention. I accomplish this object by surrounding that portion of each of the tubes exposed to radiant heat with the shields or protectors 22 which serve virtually as a secondary source of radiant. heat distributed substantially uniformly around the lower portion of the tubes comprising about one-half their surface. In adspaces 24, and will be available for heating the upper portion of the tube surfaces by radiation and convection from the gases as well as reradiation from the heated roof of the furnace. In this manner the quantity of heat absorbed by the lower half portion of each of the tubes will be relatively diminished and will be more evenly distributed over said lower'half portion,

and the quantity of heat absorbed by the upper half portion of said tubes will be relatively increased, thereby subjecting substantially the entire surface of each of the tubes to a more uniform quantity of radiant heat.

If desired, the character of the products-of combustion introduced into the combustion chamber 5 through the central combustion tunnel H may be altered or controlled in the combustion zone of the furnace to give different degrees of flame luminosity and flame temperature by varying the proportion of secondary air and primary air. This may be accomplished by introducing greater or smaller quantities of secondary air and/or by altering the products of combustion by the introduction of excess air or inert gas through either or both of the tunnels l2 and I3. The radiant properties of the products of combustion may also be increased by the introduction of steam or carbon dioxide through either or both of tunnels l2 and I3.

'In addition, a thermo-siphon may be effected within the combustion chamber 5 of the'furnace, the combustion gases therein taking the path indicated by the arrows 26. The hot combustion gases discharged from tunnel Ill along the floor into combustion chamber 5 may be directed to wall 6 so that the floor and the wall 6 become relatively hot. Said 'gases may pass upwardly along said wall and may come in contact with the relatively cool surfaces of the protectors 'oil.

or shields 22. Said gases by this contact become cooled and will pass downwardly through space 20 and adjacent tubes 19 and will again come in contact at the lower end of said space with the 'hot combustion gases freshly introduced into the shields the effectiveness of the heating element as manifest by increased capacity or throughput was increased some 15 percent when shields were used in the first two rows of the,

convection heat bank.

I claim as my invention:.

1. In combination, a furnace, a combustion chamber and a convection chamber within said furnace, a plurality of spacedly disposed heating tubes within said combustion chamber, metallic shields associated with and spacedly disposed from said tubes to afford a source of radiant heat for the lower portion of the same, a reradiating surface adjacent the upper portion of said tubes, spaces between said metallic shields through which combustion gases may pass to said reradiating surface, means associated with said metallic shields to control the quantity of combus tion gases passing to said reradiating surface, and means for passing combustion gases after passage through said shields and over said reradiating surface to said convection chamber.

2. In combination, a furnace, a combustion chamber and a convection chamber within said furnace, a plurality of spacedly disposed heating tubes mountedwithin said combustion chamber, metallic shields spacedly disposed from and surrounding the lower portions of said tubes and affording a source of radiant heat-for the same, a reradiating surface disposed above said tubes affording a source of heat for their upper portions, communications between said metallic shields for passing combustion gases from said combustion chamber between said shields and onto said reradiating surface, further means forv controlling the amount of combustion gases passing between said shields so as to effect a uniform heating of the tubes within said combustion chamber, and means for passing spent combustion gases from said combustion chamber onto a plurality of heating tubes disposed within said convection chamber.

3. In combination, a furnace, a combustion chamber within said furnace, a plurality of fluid conduits within said combustion chamber, a plurality of concentric shields associated with said conduits and adapted to provide a source of radiant heat therefor, a re-radiatlng surface oppositely disposed from said concentric shields and said conduits, means for supplying heat to* said combustion chamber and shields, and means interposed between said shields for uniformly distributing heating gases over said shields and said re-radiating surface.

4.In combination, a furnace having a heat radiant wall and a source of heat, heating tubes between said wall and the heat source and arranged to receive radiant heat on one side thereof from the wall, and a heat radiant shield surrounding and spaced from the opposite side of each of the tubes, the shields being spaced from each other to permit direct transmission of heat from theheat source to said wall.

5. In a furnace having a heat radiant roof and heating means adjacent the lower portion thereof, the combination of a horizontal row of heating tubes adjacent the roof, the upper sides of the tubes being exposed to the radiant heat of the roof, and a heat radiant shield surrounding and spaced from the lower side of each of the tubes, the shields being spaced from each other to permit direct transmission of heat from the heating means to the roof.

mailman. 

